Field of the Invention
The present invention relates to a fuel cell stack.
Background Information
Fuel cells directly convert chemical energy to electrical energy through an electrochemical reaction using an anode gas such as hydrogen and a cathode gas such as air as reaction gases.
Japanese Laid-Open Patent Application No. 2010-123377 discloses a fuel cell unit including an electrically insulating frame, a membrane electrode assembly integrally formed with the frame, and a pair of separators disposed on both sides of the membrane electrode assembly and sandwiching the membrane electrode assembly therebetween. The fuel cell stack is formed by layering a plurality of fuel cell units. In this fuel cell stack, outer circumferential sections of adjacent frames are joined by bonding members, ensuring insulation between the interior and the exterior of the fuel cell stack.
Broadly speaking, there are two methods of assembling a fuel cell stack. The first method is to sequentially layer a plurality of fuel cell units to assemble the fuel cell stack in one step. The second method is to first layer a plurality of fuel cell units into cell modules, then layer a plurality of cell modules to assemble the fuel cell stack. Assembling a fuel cell stack according to this second method yields the advantage of allowing for a reduction in the number of steps in the assembly process (see Japanese Laid-Open Patent Application No. 2010-123377, paragraph 0057).